Comparison of fatigue performance of TC4 titanium alloy welded by electron beam welding and laser welding with filler wire

Abstract

This research compared high‐cycle fatigue (HCF) performances of joints of Ti–6Al–4V titanium (TC4) alloy with the thickness of 30 mm welded by vacuum electron beam welding (EBW) and laser welding with filler wire (LWFW) (hereinafter referred to as EBW and LWFW joints). Under test conditions, the fatigue strength of the LWFW joint is only 65% that of the EBW joint. Based on analysis, the main reason is that a larger microhardness gradient is present in the LWFW joint. The average microhardness of the weld metal (WM) of the LWFW joint is 41 HV lower than that of base metal (BM). A lot of punctate β phases in the WM of the LWFW joint may be an important reason for its softening. The research results provide data supports for the application of the EBW and LWFW of Ti alloy in the field of aviation manufacturing.

Microstructure and Mechanical Properties of Arc Zone and Laser Zone of TC4 Titanium Alloy Laser–TIG Hybrid Welded Joint

“…Fu et al [20] conducted a study on underwater laser welding of titanium alloy and showed that the α martensitic sheet becomes thinner due to a higher cooling rate. Long et al [21] conducted laser welding on TC4 titanium alloy; the results show that a large amount of point-like β phase in the weld will reduce its hardness, and the fatigue strength of laser welded joints is lower than that of vacuum electron beam welded joints. Therefore, under different welding heat sources and cooling conditions, titanium alloys will cause differences in the composition of precipitates, grain size, and microscopic morphology, which affect the mechanical properties of welded joints.…”